[libFuzzer] refactor the way we choose the element to cross-over with, NFC (expected1); add a flag -seed_inputs= to pass extra seed inputs as file paths, not dirs

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@353494 91177308-0d34-0410-b5e6-96231b3b80d8
6 files changed